You wait for months for a new Super Compressor case and then two come along at once… The new Alpina Seatrong Heritage Diver watch follows closely on the heels of the Longines Legend Diver watch release, which we covered last week. Super Compressor technology was developed in the 1950s by Ervin Piquerez SA (EPSA) and is a particular type of case construction with a sprung back, designed to increase water resistance as the external pressure on the watch grows.
How does it work? Well, the caseback of a Super Compressor watch is either threaded or a bayonet fitting (like you might expect to find in a light bulb), and fitted with a strong spring that prevents the caseback from screwing all the way down. Instead, the tension is adjusted so that the caseback makes contact with (and only partially depresses) the rubber seal (gasket or o-ring). Before the gasket can be fully compressed, the tension in the spring resists (when above sea level) and ensures that a certain amount of theoretical play is left in the gasket. As the diver descends and the water pressure around them increases, the caseback is crushed into the gasket, further flattening the seal and, thusly, increasing water resistance.
The Alpina Seatrong Diver collection is, well, strong. It’s a tastefully designed collection that screams vintage appeal. The latest addition is a 42mm stainless steel case with a bronze color PVD coating. It is interesting that Alpina opted not to make this watch out of bronze entirely (obviously it is cheaper to make a steel case and simply coat it to appear as if it is crafted from bronze) because it speaks volumes of bronze’s continued aesthetic popularity. With a PVD coating, there will be none of the usual patina you would expect with a genuine bronze case, which will please some and rankle others (from either a stylistic or congruity perspective, I imagine).
This watch is water-resistant to 300 meters. It is 12.3mm thick and boasts a sapphire crystal on the front and an engraved caseback. It is powered by the AL-525 automatic caliber (a modified caliber based on the Sellita SW200, but with a really nice off-center rotor weight), which boasts 26 jewels, a 38-hour power reserve, and an operating frequency of 28,800vph. Both crowns are decorated, one with with the hatching one would expect to find on a traditional Super Compressor, and one with the Alpina logo. They also have much thicker grooves cut into their sides, which is a more modern take on the classic design. Crucially, both crowns are screw-down. That’s a real boon as one of the major (and pretty blatant) criticisms of a Super Compressor is that the crown that controls the (often bidirectional) inner bezel is vulnerable to potentially disastrous knocks, should a diver accidentally lengthen the time they are able to spend underwater by shunting the inner bezel in a clockwise direction.
The brown dial is a chromatic match made in heaven for the bronze-colored case. The sunray finishing adds a dash of vintage flair, while the white date window between 3 and 4 o’clock just about hangs together with the design thanks to the thin strips of (almost) white Super-LumiNova on the hands, and the bezel dot at 12 (it’s actually a very pale green). I would have liked to have seen much more lume on the dial to convince me that this was really meant to be a tool watch and not just an office poser, but there are enough required features for it to be dive-ready so I won’t gripe about it too much. There is also a second variant of this watch available (reference AL-525BRC4H4) that has a white inner bezel. That one works very nicely with the date from a colorway angle, but I personally prefer the rich chocolatiness of the pictured model here.
This particular model (AL-525BR4H4) is a really pleasant addition to an already strong offering. With a retail price of $1,795, it is a little more than the standard Seastrong Super Compressor (which retails at $1,460) but the unusual perma-bronze PVD coating does give it a completely distinct character and makes it a tempting addition to a collection that craves color variation. The Alpina Seastrong Heritage Diver comes on a brown leather strap and with a spare rubber option included. Learn more at alpinawatches.com.